Nations can only have an advanced structure and mobile society if they have paved roads, railroads, airports, dams, buildings, foundations for houses, and countless other things that require crushed rock and other rock products; in fact, all people live in an ongoing Stone Age and always will. The volumes and tonnages of sand, gravel, crushed rock, cement, and ore far exceeds any other products in the United States. As in most businesses there is substantial competition both within the producers of rock products, and also those who manufacture machinery for such purposes. Gyrating cone crushers are the machines of choice for crushing the harder and more abrasive rock. The more efficient, durable, and economical a cone crusher can be the better it serves all concerned. Rock crushers should be structurally very strong to withstand the enormous pressures imposed, yet should not be so over designed that they become too heavy and too costly. It is more logical to use portable crushing plants at nearby rock sources to the places of use than if the hauling distances are too far from stationary commercial rock sources to the places of use; plus portable crushing plants can be built for much greater production, e.g. for highway construction, than most commercial plants. Crushers for portability must be of compact dimensions and low weight consistent with acceptable capacity and low maintenance; such a machine is the subject of our request for patent rights; it has several new concepts that will prove to be extremely advantageous for both portable and stationary use.